Forge "man" pages are missing for most UI Commands

This is more a question because I don't know what man is suppose to do. This is what I get :

[Test.java]$ man grep
No manual entry for grep
[Test.java]$ man echo
No manual entry for echo

I would expect to have a manual for each Forge command and also to get completion (e.g. man jpa TAB and it will give all the JPA commands available in the manual